Vitamin D Does a Body Good

Chronic pain: Vitamin D deficiency is increasingly recognized as a cause of muscle pain and weakness.

Autoimmune diseases: Studies show vitamin D may offer protection from type-1 diabetes, multiple sclerosis, and rheumatoid arthritis by strengthening the immune system and reducing inflammation. In one study, researchers found a 40 percent lower risk of MS in women who supplemented their diet each day with at least 400 IU of vitamin D.

Osteoporosis: A decrease in muscle strength can increase the risk of falls and bone fractures as we age, but studies have found that supplementing with vitamin D may benefit both muscle strength and balance. Vitamin D also helps the body absorb calcium. Note: The body produces vitamin D when exposed to the rays of the sun, but most people still need a supplement—between 800 to 1,000 IU daily—to reach recommended levels.